Thickened hypochlorite bleach solutions or compositions have long been used in a variety of applications including hard surface cleaning, disinfecting and the like. These compositions are typically provided with increased viscosity for a number of reasons, principally to increase residence time of the composition on non-horizontal surfaces.
Many different examples of thickened hypochlorite bleach compositions have been available from a wide variety of sources for use in hard surface cleaning. For example, Finley et al., European Patent Application EP 373,864 and Prince et al., U.S. Pat. No. 5,130,043, disclosed hypochlorite bleach compositions consisting of polyacrylate thickeners, amine oxide detergent, and optional fatty acid soap and/or a bleach stable synthetic anionic detergent for cleaning hard surfaces such as toilet bowls, bathroom tiles and shower walls. Other prior art references have also described various thickened automatic dish washing liquid compositions using polyacrylates in combination with colloidal thickeners to provide proper rheology and stability in hypochlorite bleach compositions including various adjuncts. Stoddart, U.S. Pat. No. 4,576,728, and Corring, U.S. Pat. No. 4,836,948, are representative of these other prior art references. However, as can be seen from the disclosures of each reference, there must be a polyacrylate thickener present in order to obtain the desired viscosity.
Additionally, other examples of thickened hypochlorite-containing cleansers in the art, which usually are used to suspend abrasives, typically require either a colloidal clay thickener, such as disclosed in Hartman, U.S. Pat. Nos. 3,985,668, 4,005,027 and 4,051,056, a mixture of surfactants, such as disclosed in Jones et al., U.S. Pat. No. 4,352,678, or a stearate soap, such as disclosed in Chapman, U.S. Pat. No. 4,240,919. All of these systems suffer from disadvantages, such as premature hardening in the colloidal clay-thickened systems, or poor phase stability, as in the stearate-thickened systems.
Some references describe the unique phenomena that occurs when certain charge-bearing surfactants, such as quaternary ammonium compounds or betaines, are combined with a source of a counterion. U.S. Pat. Nos. 4,900,467, 5,011,538 and 5,055,219, all issued to Smith (and of common assignment herein), provide exemplary cleaning compositions generally characterized as viscoelastic.
There are a number of somewhat slightly thickened hypochlorite bleaching liquids, such as Citrone, U.S. Pat. No. 4,282,109, Joy, U.S. Pat. No. 4,229,313, Schilp, U.S. Pat. No. 4,337,163, Hynam et al., U.S. Pat. No. 3,684,722, and Vipond, U.S. Pat. No. 4,775,492. Generally, however, each of these references discloses relatively thin liquids having relatively high amounts of surfactants which function as hydrotropic materials. These types of liquid bleaching compositions, because of their lack of body, generally cannot be effectively dosed onto vertical or curved surfaces.
Published European patent applications EP 0336651 and 033652, of common assignment herewith, discloses thickened aqueous cleaning compositions, one of which can contain abrasives, both of which are thickened by the combination of surfactants and aluminum oxide, and both can have certain organic solvents present to assist in cleaning performance. Neither product is a gel. However, polymer-thickened bleach-containing systems need to be packaged in opaque packaging, since ultraviolet wavelength light may accelerate decomposition.
A related application, Choy, U.S. patent application Ser. No. 07/780,360, filed Oct. 22, 1991, now U.S. Pat. No. 5,279,758 of common assignment herewith, discloses a thickened hypochlorite composition in which alkyl ether sulfate surfactant and certain solvents are combined to provide an advantageously thickened liquid cleaner. Yet another beneficially thickened gel cleaner, which used polyacrylate as a thickener, was described in Garabedian et al. (U.S. patent application Ser. No. 08/097,738, filed Jul. 27, 1993, of common assignment herewith). The disclosures of these latter two applications are incorporated herein by reference thereto.
Generally, the prior compositions have performed satisfactorily for their intended purpose. However, there is a need for thickened gel cleaner containing hypochlorite bleach with improved thickening and bleach stability, offering improved characteristics and benefits.